The 2019 McLaren Senna is not pretty. But if you believe form should follow function, it’s beautiful. Every dramatic curve, every nuanced surface, every tiny detail has earned its place on this car for one simple reason, says McLaren Automotive CEO Mike Flewitt: to make the McLaren Senna the most exciting street-legal car you can drive on a racetrack.

That’s quite a mission statement in an era of impressive track-focused road cars such as the Porsche 911 GT2 RS, Lamborghini Huracán Performante, and the Mercedes-AMG GT R. But the McLaren Senna’s got game. It represents nothing less than weapons-grade performance engineering from a company with decades of experience at the highest levels of motorsport and a reputation for creating extraordinary hypercars.

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McLaren Automotive engineering design director Dan Parry-Williams describes the Senna as a mashup between the P1 and the recently launched 720S, combining hardware and intellectual property from both. In simple terms, the Senna’s core structure and powertrain are derived from the 720S, and the braking system and the hydraulically modulated, computer-controlled, height-adjustable suspension are evolved from P1.

The Senna’s mid-mounted 4.0-liter twin-turbo V-8 features a new air intake and carbon-fiber plenum, unique lightweight cams and pistons, new sensors that allow higher combustion pressures and temperatures, and two high-flow fuel pumps. It develops 789 hp at 7,250 rpm and 590 lb-ft from 5,500 rpm to 6,700 rpm, increases of 78 hp and 22 lb-ft over the 720S engine.

Those are big numbers, especially for a car McLaren knows will likely accumulate more miles on the track than it will on the road. “Track mileage is hard on engines,” concedes Parry-Williams. “If we weren’t worried about durability, we could just keep pushing the power up, but I think we’re close to the limit of what we can get out of this engine with that kind of duty cycle.”

The engine drives the rear wheels through the same seven-speed dual-clutch transmission used in the 720S, but it’s tuned to deliver faster shifts. McLaren claims the Senna will sprint from 0 to 60 mph in 2.7 seconds, but we’ve just had a 720S post a stunning 0–60 time of 2.5 seconds in our instrumented testing, so that number might be on the conservative side. Even so, spec-sheet mavens—who’ll also note the Senna’s 211-mph top speed is identical to that of the 720S—will no doubt ask the question: Why pay an eye-watering $958,966 for a car that at first glance seems no quicker than the $288,845 720S?

Two reasons: low weight and high downforce.

A truly fanatical—and not inexpensive—attention to weight reduction (see below) has peeled away the pounds: McLaren claims the lightest version of the Senna weighs a feathery 2,641 pounds without fluids. Call it about 2,900 pounds, gassed and ready to go, and the Senna is at least 200 pounds lighter than a 720S. Simple physics suggests that weight advantage, combined with its grippier, specially developed Pirelli P Zero Trofeo R tires and latest-generation CCM-R carbon-ceramic brakes, means it should be significantly nimbler into, through, and out of corners than the 720S.

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But wait, there’s more. Selecting Race mode lowers the front of the Senna 1.5 inches and the rear 1.2 inches to optimize the carefully designed aerodynamic floor’s angle of attack on the airflow. This, the active aero blades tucked in the gaping apertures under the headlights, and the giant active rear wing towering over the Senna’s low-slung hindquarters help deliver a staggering 1,764 pounds of downforce at 155 mph. The computer-controlled aero blades and wing also automatically trim themselves to maintain that level of downforce right through to 211 mph. Under brakes the aero blades bleed off downforce at the front of the car while the rear wing moves to increase downforce on the rear axle, ensuring balance and stability.

McLaren engineers claim the Senna generates the highest downforce of any road car in the company’s history: 40 percent more than a P1, to be precise, delivering 30 percent more lateral grip though corners. “We’re looking for a car that’s agile and stable,” Parry-Williams says. “That’s the great thing about active aero—you can have both.”

The Senna’s on-track mission is simple: to turn a faster lap time than the P1. In addition to superior grip, the Senna has a 400–500-pound weight advantage and a slightly superior weight-to-power ratio: 3.67 lb/hp versus 3.77 lb/hp (those lithium-ion batteries in the P1’s 904-hp hybrid powertrain are heavy). So it’s safe to assume McLaren can hoist the “Mission Accomplished” banners even before we put our in-house hot shoe Randy Pobst behind the wheel of the Senna to challenge his own P1 lap time at Laguna Seca.

McLaren Automotive design director Rob Melville says he approached the Senna almost as if it were a piece of military equipment, designed purely for purpose, celebrating its uncompromising focus on track performance. “My approach to aesthetics is to understand the problem we’re trying to solve with the design of the car,” he says. “I don’t force an aesthetic onto a project. It should be as a result of answering those questions.”

There isn’t a line on the Senna that runs from front to rear without passing through a functional intake or vent. Viewed from above, the teardrop-shaped central form of the 720S’ cabin and engine compartment is surrounded by four sheer-sided and sharp-edged pods that are designed to optimize the airflow around the wheels and along the sides of the car. “We need quite square corners on the car because these are powerful in terms of generating the aero that we need,” Parry-Williams says. “You can fight against this stuff or embrace it.” The Senna gives it a giant bear hug. You want pretty? Buy a Lamborghini Huracán.

The uncompromising design approach brings other benefits. Improving airflow along the sides of the car and into the rear ducts allows for simpler, lighter, single-skin doors that feature what will become a signature design element of the Senna—glass panels. Made from aircraft-grade material, the panels make sitting inside the Senna an absolutely unique experience: The road is right there in your peripheral vision at all times, emphasizing how close you’re riding to the tarmac.

Whereas the exterior of the Senna is all aerodynamic flamboyance, the interior is stripped back minimalism. If you see carbon fiber, it’s structural, not decorative. To help save precious ounces, few interior surfaces are covered. Even the gas struts that hold the doors open have been left in plain view. The fixed-back seats are simply thin, carbon-fiber eggshells with seven separate, strategically placed pieces of foam attached. (They feel surprisingly comfortable.) The gear selection buttons are housed in a small carbon-fiber binnacle attached to the lower inner edge of the driver’s seat.

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Whatever the Senna driver is likely to need in the heat of a hot lap is close to hand. Compared with the 720S, the central touchscreen and vehicle-setting controls have been moved higher and angled inward. The less important stuff, such as the power window buttons, has been moved to a roof-mounted pod.

Just 500 McLaren Sennas will be built, and all have already been sold, with about a third of them coming to the U.S. Is it the ultimate track rat? Well, Porsche’s stunning 911 GT2 RS currently holds the Nürburgring Nordschleife road car record with a blistering 6:47.3 lap. But the alpha-dog 911 has almost 100 fewer horses than the Senna, weighs at least 200 pounds more, and generates 43 percent less downforce at top speed. You do the math.

LEGENDS REUNITEDTwo of racing’s most famous names are back together

McLaren Senna. Magic, right there. Ayrton Senna became a three-time world champion at the wheel of a McLaren Formula 1 car in just four years. Now, almost a quarter century later, the two names are reunited.

Senna was reckoned by many to have been the greatest F1 driver of all time. The preternaturally gifted Brazilian’s understanding of vehicle dynamics was legendary in pit lane. “He could talk for one hour about a single lap of Monaco, describing everything that the car was doing, what was happening, and why,” says Andy Palmer, McLaren’s Ultimate Series vehicle line director.

Senna dabbled in road car development while at McLaren, working with Honda (then the McLaren F1 team’s engine supplier) on the final chassis tune of the original NSX. Had he not been tragically killed in the 1994 San Marino GP at Imola (after he’d left McLaren to drive for rival team Williams), the experience might have spurred involvement in other road car projects.

“It was Ayrton’s dream to have a car with his name on it,” says nephew Bruno Senna, himself a former F1 driver. And now he has.